1. Field of the Invention
This invention relates to a metal-ceramic composite for use in a heat-resisting member such as a supporting member of a heating furnace, in particular to a metal-ceramic composite, in which a ceramic is added to a matrix formed of a heat-resisting metal or alloy, and a method of producing the same.
2. Description of the Prior Art
In general, various kinds of characteristic, for example oxidation resistance compression resistance, thermal shock resistance, superior weldability, long time stability at high temperatures, mechanical shock resistance and the like, are required for a supporting member such as a skid button of a heating furnace of a slab and the like.
And, heat-resisting alloys, such as heat-resisting alloys of 30Cr-50Co-Fe series and heat-resisting alloys of 27Cr-40Co-20Ni-Fe series, have been used for the supporting member but the use of a single metal is limited in scope of use due to a defect that a creep deformation is apt to occur. One the other hand, the use of ceramics as a substitute for heat-resisting alloys is naturally thought of but the practical use of a single ceramic has a problem due to a low shock-resisting strength of ceramics.
Thus, in order to improve this problem, a composite, in which a metal having a superior toughness is used for a matrix and ceramic particles having a superior abrasion resistance are dispersed in the matrix, is thought of. And, this sort of composite has been developed and some kinds of metal-ceramic composite and method of producing the same have been already proposed. The main metal-ceramic composites and methods of producing the same, which have been recently proposed, are listed as follows:
(1) A method in which a ceramic particle-containing layer is laminated on a backing strip formed of a matrix metal and an assembly is pressed in a semi-melting temperature range of the matrix metal (Japanese Patent Application Laid-Open No. 58-153706).
(2) A method in which ceramic particles are dispersed in a semi-molten matrix metal with stirring, a ceramic particle-dispersed material obtained by molding the dispersion being laminated on a backing strip formed of the same material as the matrix metal, and the assembly being pressed in a semi-melting temperature range of the matrix metal (Japanese Patent Application Laid-Open No. 58-153706).
(3) A method in which ceramic particles are uniformly scattered on a surface of a matrix metal and the assembly is pressed in a semi-melting temperature range of the matrix metal (Japanese Patent Application Laid-Open No. 58-153706).
(4) A molten metal-forging method in which a molten metal (Al) forming a matrix is poured in a mold, which is prepacked with particles to be dispersed, from an upside and pressurized from an upside (Eiichi Nakada: A molten metal-forging as a composite techonology, Metal, 1982, p. 19-22).
(5) A method in which composite particles obtained by the occlusion of hydrogen by a ceramic powder-hydrogen occlusion active metal composite are mixed in a molten matrix metal (Japanese Patent Application Laid-Open No. 59-93846).
However, the above described composites and method of producing the same have shown the following problems:
With the arts (1) to (3), particles can be dispersed only in a metallic surface, so that a packing ratio of particles can not be increased, whereby the weight can be only to a small extent. In addition, a compression strength at high temperatures is low and a highly insulating metal-ceramic composite can not be obtained. Besides, a metal-ceramic composite produced by methods according to (1) to (3) is unsuitable for a supporting member of parts complicated in shape since particles are predominantly included in a surface, whereby a shape, in which particles exist on the surface, can not be always obtained after cutting.
Furthermore, with the art (4), the particles are apt to be damaged by a thermal shock in a casting process of a molten metal and gases existing among particles and gases produced in the casting process are difficult to remove since a molten metal for use in a matrix is poured on the particles to be dispersed, so that cavities are formed in a product to deteriorate the quality.
In addition, with the art (5), the particles to be used are limited to ceramics (alumina, zirconia and the like), which strongly bond with active metals such as Ti, Zr, Ta and Nb, and a complicated process of occluding hydrogen by the metal is required.